Method of and apparatus for producing filled precious-metal wire, &amp;c.



vF. KAMMERER.

METHOD OF AND APPARATUS FOR PRODUCING FILLED PRECIOUS METAL WIRE 6w.

APPLICATION FILED DIJO.27,1913.

fnyenz'or'u object to permit the application to the sup- UNITED STATES PATENT OFFICE.

FRIEDRICH KA MMERER, F PFORZHEIM, GERMANY.

METHOD OF AND APPARATUS FOR PRODUCING FILLED PRECIOUS-METAL WIRE, 80c.

Specification of Letters Patent.

Patented May 12, 1914.

Application filed December 27, 1913. Serial No. 808,956.

To all whom it may concern:

Be it known that I, Fnmomon KAMMERER, a subject of the Grand Duke of Baden, and a resident of Pforzheim, Germany, have invented certain new and useful Improvements in the Method of and Apparatus for Producing Filled Precious-Metal Wire, &c., of which the following is a specification.

This invention relates to a novel method of producing filled precious metal wires, sheets and other articles of manufacture, which method has more particularly for its porting core, of a mantle of gold, etc., which although being of but a minute thickness is not liable to scale off, and does not possess any fissures, cracks or other deficiencies that would render the manufactured article unfit for subsequent working or chemical treatment.

The invention comprises also novel means by which my improved method may be carried into effect,

With the methods hitherto generally employed, a suitable core of substantial diameter was surrounded with a sheet of gold or another precious metal, and the diameter of the core thus covered was radually reduced by rolling, drawing and pressing to such an extent that the resulting article represented a long fine filled gold, etc., wire.

latter, the gold film is usually not rolled down to an extreme fineness, but is left unreasonably thick, so that the finished prodnot is comparatively expensive. These and other inherent disadvantages of the old methods have been overcome by my novel method according to which the base metal core, before being surrounded by a gold film, is rolled or drawn down to approximately the fineness which it is to possess 1n.

the finished article, whereupon it is passed through a galvanic gold, etc., bath. As the electrolytic gold deposit thus formed on the core is, however, brittle and liable to scale off, a further treatment is necessary in order to transform the electrolytic deposit into a homogeneous tenacious film which should be intimately united to the core. This further treatment consists in simultaneously subjecting the gold covered wire to'a high temperature and to a high pressure. The temperature should lie between approximately 750 and 800 degrees Centigrade, or

in other words the temperature should be slightly lower than that at which a softenmg of the core and a welding or fusing would take place between the'core and the gold deposit. In this way an eventual absorption of the gold by the core is entirely obviated, which absorption if allowed to take place, would correspondingly reduce the thickness of the remaining gold film. On the other hand, it is necessary for obtaining the necessary ductility of said film, that the comparatively loosely precipitated particles of gold and of the other ingredients constituting the electrolytic deposit, such as those of the silver and copper additions, be

intimately united or fused together. As the temperature is limited for this purpose owing to the relatively low melting point of the base metal core when compared with that of the gold covering a high pressure is applied to the heated gold covered wire. In this way a homogeneous gold film is formed on the core which is free from'fissures and other deficiencies. So also the process has marked advantages over those hitherto generally practised in'the art. These advantages consist in considerably lowering the cost of manufacture of filled gold wire, be cause the waste is greatly lessened, owing to the fact that the diflicult operation of gradually rcducing the comparatively thick core and the surrounding gold sheet into a wire of the desired fineness is entirely done away with. With my -method, the inexpensive core may be rolled or drawn down by unskilled help for the reason that the expensive gold is only applied after the completion of this operation. Furthermore the thickness of the gold film may with my ,method be reduced to about one third of that obtainable with the old methods so that a considerable saving of the precious metal is effected.

My improved method may be practised in an apparatus diagrammatically illustrated in the accompanying drawing in which- Figure 1 is a longitudinal section thereof, and Fig. 2 a plan.

A plurality of core wires 10 which have been previously reduced to the desired tineness by suitable means (not shown) are simultaneously drawn in a zig-zag course through a galvanic gold, etc., bath 11 to be there provided with the desired precious metal coating. At its entrance to and exit from the bath, each wire runs over a conductive roll 12 which is by wire 13, connected to the negative pole of the source (not shown) that supplies the bath with electric current. Within'the bath, there is contained a suitable number of staggeringly arranged guide rolls 14 supported by transverse shafts 15 so as to impart to the wires the zigzag course desired. The anode wires 16 are connected to the positive pole of the source and are arranged substantially in a circle around the path of each wire 10. After wires 10 havethus been provided with the necessary deposit of the precious metal, they are fed through corresponding passages 17 formed in an oven 18 to which a suitable heating medium such as gas and air is admitted through burner pipe 19. Within each passage 17 is arranged a pair of pressing and drawing rolls 20 that also serve to advance the wire through'bath 11. Rolls 20 and their bearings are preferably made of quartz glass, zircon glass or other highly fireproof glass fluxes. The coefficient of expansion of these fluxes is so small, that their dimensions willpractically not change under different temperatures, so that the pressureto which the gold deposit is-to be subjected, may be exactly calculated. Such a precision ""of the amount of pressure applied is necessary, as otherwise the gold deposit may be stripped off by the rollers before its particles have become properly united. After this operation has taken place, the filled gold wire is homogeneous film and binding it to the core by applying mechanical pressure to the coated core at consecutive pointsand simultaneously subjecting the coated core at its point of compression to exterior-1y applied high temperature which lies however below the softening point of the core metal.

2. Apparatus for producing filled precious metal articles of the class described, comprising a galvanic precious metal bath, means for conducting a base metal core through said bat-h to provide it with an electrolytic preciousmetal coating, a pair of rolls adapted to compress the coated core, and means for subjecting the rolls and the coated core at its place of engagement with the rolls to exteriorly applied high temperature which lies however below the softening point of the core metal.

IRWIN KAMMERER, S. S. BERGER. 

